Restarting DHCP safely whilst avoiding partner-down state

[Terry Burton]

On 13 May 2016 at 15:57, Chuck Anderson <cra at wpi.edu> wrote:
> On Fri, May 13, 2016 at 03:23:25PM +0100, Terry Burton wrote:
>> On 13 May 2016 at 14:22, Chuck Anderson <cra at wpi.edu> wrote:
>> > I don't know if a corrupted lease file would cause a failure to start
>> > the dhcp server, or if it would just go unnoticed, perhaps with a log
>> > message.  But like I said, we've never had a failure to start the
>> > server that was caused by a lease file issue.
>>
>> In our experience leases files corrupted by other means can cause a
>> failure to start. I don't recall whether that was due to mere
>> truncation though...
>
> There is also the -T parameter to test the lease file:
>
>        The -T flag can be used to test the lease database file in a similar way.
>
> It might be a good idea to also use this test before restarting.
> While it won't fix a corrupted lease file, it may prevent you from
> losing all DHCP service due to a failure to restart.

I think this will require the leases file to be closed at the point of
testing, i.e. the daemon has already exited.

For the more general issue with systemd verifying the configuration
see: https://lists.freedesktop.org/archives/systemd-devel/2016-May/036481.html